The present invention relates to medical devices and more particularly to an illuminating lamp for producing either a focused line of light or diffused light and used especially by ophthalmologists as an auxiliary lamp on a slit lamp in eye examinations and photographic documentation.
A widely used instrument used by ophthalmologists for eye examinations is called a xe2x80x9cslit lampxe2x80x9d biomicroscope (slit lamp diagnostic microscope). The instrument consists, generally, of fixed-frame posts supporting a headrest to receive the chin and forehead of a patient, and a movable base. A stereomicroscope is mounted on the base and the base is moved, in the X-Y-Z directions, by the user. A lamp is mounted to shine on the eye being examined and a control device, in front of the lamp, produces a slit of light, e.g., an elongated line of light of about 100,000 to 600,000 Lux.
That slit of light is focused on the patient""s eye. Some slit lamps permit the length of the beam to be changed, i.e., 0.2 to 8 mm or more, and to be rotated about the patient""s head and to be angled, i.e., rotated 20 degrees from vertical. The ophthalmologist looks at the eye being examined, generally through a stereo microscope mounted on the stand and also through a lens which is generally held by hand.
This type of slit lamp is available from Haag-Streit AG, i.e., Model 900 BQ; Rodenstock, i.e., Model RO 5000; Reichert, i.e., Model Xcel; D. F. Vasconcellos; Nikon; and others.
Although this type of slit lamp has proven satisfactory for eye examinations, it is not adapted for precision electronic/digital photography of the eye. For example, in xe2x80x9ctelemedicinexe2x80x9d a patient at a local facility (for example, a small-town ophthalmologist office) is being examined. A photograph (video or still picture) of his eye is transmitted, in real time, to a center (for example, a university hospital) to obtain a consultation by a cornea specialist. A picture of the eye is taken using a high-resolution color digital camera, transmitted over a broadband telecommunication channel and displayed on a high-resolution monitor. However, the picture may not be satisfactory to provide an accurate remote diagnosis because the slit lamp""s illumination of the patient""s eye is not illuminated satisfactorily for accurate photography. The ophthalmologist, using his eyes and skill, can see more than shows in a high resolution digital photograph.
U.S. Pat. No. 5,196,874 is entitled xe2x80x9cSlit Lamp Apparatus With Peripheral Illumination.xe2x80x9d It, and the present invention, provide an auxiliary lamp (additional illuminating device) to shine on the eye undergoing examination in addition to the slit illuminating device. The ""874 patent""s auxiliary lamp is a tube which is rotatably mounted on the slit lamp frame.
Other patents that relate to slit lamps include U.S. Pat. Nos. 4,868;383; 3,403,957; 5,099,354; 3,652,153; and 5,018,851; the above-listed patents being incorporated by reference.
In accordance with the present invention an auxiliary lamp is provided. A finger-operated knob moves a cylindrical lens to provide either a focused line of light or diffused light. One or two of these auxiliary lamps are used, in addition to the conventional slit lamp, to provide side illumination on an eyeball undergoing examination, especially for accurate digital photography of the eye.
The light is generated by a bulb within a lamp housing. The bulb and housing are used to generate light to a fiber optic bundle. An adjustable filter disc is positioned between the bulb and the fiber optic bundle to vary the amount of light reaching the fiber optic bundle. In addition, heat (IR) and UV filters are provided to remove heat and UV (Ultra-Violet) from the light beam before it reaches the optic fiber bundles. The disc has a series of zones and each zone has holes of a uniform size. The size of the holes differs as between zones. As the disk is rotated either more, or less, light passes through the disk. The disk controls the amount of light transmitted from the bulb to the fiber optic bundle without altering the light""s color temperature.
A fiber optic connector is positioned on the lamp housing and has two inputs to receive two fiber optic bundles (left and right bundles). Each fiber optic bundle leads to an auxiliary slit lamp. The fiber optic bundles are random bundles of fine glass optic fibers, for example, 1,000-10,000 fibers in each bundle, and each bundle is protected by a flexible sheath.
Each auxiliary lamp is at a free end of an optic fiber bundle. The auxiliary lamp consists of an elongated and flat housing whose height is about the height of the normal eye socket, i.e., 1.5 to 2.5 cm. The ends of the fibers are randomly arranged and firmly held in the housing, arranged and glued to form an elongated rectangular end face line viewed from the end, i.e., 2 cm long and 0.2 to 0.5 mm wide. A cylindrical lens is positioned in front of the end face of the fiber optic bundle (line) to focus the light. Preferably the lens is elongated, i.e., 2 cm in height, and round in cross-section. A finger-operated knob and screw mechanism, on the housing, mounts the lens and allows its movement toward, or away, from the fiber bundle end face to focus or to diffuse the light. The light may be micrometrically focused to form a line of light, or may be unfocused to form a diffused illumination. The line of light provides a preset focus to enable viewing and photography in sharp focus of the eyelids, cornea, iris and the anterior part of the natural lens.
The auxiliary lamp housing is preferably mounted on a fixed post of the slit lamp frame using a precision double ball joint mounting device. The user may adjust the distance from the auxiliary lamp to the eye and may adjust its angle relative to the normally vertical slit lamp""s illumination.
The eye being examined is imaged using a high resolution digital still or motion camera which generates a video-compatible signal, such as the Sony DKC 5000 (Cat""s eye camera). It can produce still pictures or moving images in video resolution and digital high resolution, more than 1500xc3x971100 pixels. Two cameras mounted on either side can show stereo.
The auxiliary lamp can be used, depending on its focus as a background illuminator or to illuminate the entire cornea. Its adjustability, by movement of the cylindrical lens, permits changes in focus and also permits the width of the beam to be varied.
The auxiliary lamp produces a totally cold light which gives a constant color temperature, permitting accurate digital imaging. The use of two auxiliary lamps, with left and right fiber optic bundles, permits lighting of the same eye from two directions and, using a special device, simultaneous examination and comparison of a patient""s left and right eyes. The regular slit lamp may be turned off and the auxiliary lamp may be used to focus light on the retina.
The auxiliary lamp of the present invention is also adapted for use in eye surgery, especially corneal refractive surgery (without a slit lamp) and for close examination and surgery on the skin. In refractive surgery the lamp does not produce an objectionable reflection from the eye""s cornea.
The present invention also provides for mounting a lens, preferably an aspheric lens, on a double four-joint mount. That mount permits the aspheric lens to be accurately positioned near the eye being examined without being hand-held. The aspheric lens is mounted at a fixed distance from the microscope. The ophthalmologist""s hand is now free as it is not carrying an examination lens. The bottom of the lens mount is fixed to the movable portion of the slit lamp stand so that it moves along with the stereo microscope. This permits the digital picture, which may be a still photograph or a moving video, to be taken through the microscope and the aspheric examination lens without shaking due to hand motion.
The auxiliary lamp may be used to shine a line of light through the double convex aspheric lens in order to illuminate the retina. Its lens may be adjusted to provide either a diffused or focused light on the retina. In this use it becomes a miniature portable slit lamp.
Preferably the stereo microscope is fitted or retrofitted with an inverter. The inverter changes the image""s orientation (left to right and right to left) and the vertical direction (up to down) and provides a normal image of the eye right side up. The aspheric lens inverts the normal image and the inverter reinverts that image so the ophthalmologist sees a normal upright image. The microscope inverter""s normal image (correct side up) permits the ophthalmologist to observe the retina correct side up, to move his hand, and hand-held instruments, in a normal mannerxe2x80x94and not in reverse as would be required without the inverter. He may view the eye being examined through the aspheric lens to catch the center of the eye in the center of the microscope field of view and flip the inverter into the optical path to obtain the desired reinverted image.